Memory-corrected quantum repeaters with adaptive syndrome identification
We address the challenge of incorporating encoded quantum memories into an exact secret key rate analysis for small and intermediate-scale quantum repeaters. To this end, we introduce the check matrix model and quantify the resilience of stabilizer codes of up to eleven qubits against Pauli noise, o...
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American Physical Society
2025-01-01
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| Series: | Physical Review Research |
| Online Access: | http://doi.org/10.1103/PhysRevResearch.7.013117 |
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| author | Alena Romanova Peter van Loock |
| author_facet | Alena Romanova Peter van Loock |
| author_sort | Alena Romanova |
| collection | DOAJ |
| description | We address the challenge of incorporating encoded quantum memories into an exact secret key rate analysis for small and intermediate-scale quantum repeaters. To this end, we introduce the check matrix model and quantify the resilience of stabilizer codes of up to eleven qubits against Pauli noise, obtaining analytical expressions for effective logical error probabilities. Generally, we find that the five-qubit and Steane codes either outperform more complex, larger codes in the experimentally relevant parameter regimes or have a lower resource overhead. Subsequently, we apply our results to calculate lower bounds on the asymptotic secret key rate in memory-corrected quantum repeaters when using the five-qubit or Steane codes on the memory qubits. The five-qubit code drastically increases the effective memory coherence time, reducing a phase flip probability of 1% to 0.001% when employing an error syndrome identification adapted to the quantum noise channel. Furthermore, it mitigates the impact of faulty Bell state measurements and imperfect state preparation, lowering the minimally required depolarization parameter for nonzero secret key rates in an eight-segment repeater from 98.4% to 96.4%. As a result, the memory-corrected quantum repeater can often generate secret keys in experimental parameter regimes where the unencoded repeater fails to produce a secret key. In an eight-segment repeater, one can even achieve nonvanishing secret key rates up to distances of 2000 km for memory coherence times of t_{c}=10 s or less using multiplexing. Assuming a zero-distance link-coupling efficiency p_{0}=0.7, a depolarization parameter μ=0.99, t_{c}=10 s, and an 800 km total repeater length, we obtain a secret key rate of 4.85 Hz, beating both the unencoded repeater that provides 1.25 Hz and ideal twin-field quantum key distribution with 0.71 Hz at GHz clock rates. |
| format | Article |
| id | doaj-art-3831cc94f0534d2da0fb3c7166f0e084 |
| institution | Kabale University |
| issn | 2643-1564 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | American Physical Society |
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| series | Physical Review Research |
| spelling | doaj-art-3831cc94f0534d2da0fb3c7166f0e0842025-01-30T15:02:10ZengAmerican Physical SocietyPhysical Review Research2643-15642025-01-017101311710.1103/PhysRevResearch.7.013117Memory-corrected quantum repeaters with adaptive syndrome identificationAlena RomanovaPeter van LoockWe address the challenge of incorporating encoded quantum memories into an exact secret key rate analysis for small and intermediate-scale quantum repeaters. To this end, we introduce the check matrix model and quantify the resilience of stabilizer codes of up to eleven qubits against Pauli noise, obtaining analytical expressions for effective logical error probabilities. Generally, we find that the five-qubit and Steane codes either outperform more complex, larger codes in the experimentally relevant parameter regimes or have a lower resource overhead. Subsequently, we apply our results to calculate lower bounds on the asymptotic secret key rate in memory-corrected quantum repeaters when using the five-qubit or Steane codes on the memory qubits. The five-qubit code drastically increases the effective memory coherence time, reducing a phase flip probability of 1% to 0.001% when employing an error syndrome identification adapted to the quantum noise channel. Furthermore, it mitigates the impact of faulty Bell state measurements and imperfect state preparation, lowering the minimally required depolarization parameter for nonzero secret key rates in an eight-segment repeater from 98.4% to 96.4%. As a result, the memory-corrected quantum repeater can often generate secret keys in experimental parameter regimes where the unencoded repeater fails to produce a secret key. In an eight-segment repeater, one can even achieve nonvanishing secret key rates up to distances of 2000 km for memory coherence times of t_{c}=10 s or less using multiplexing. Assuming a zero-distance link-coupling efficiency p_{0}=0.7, a depolarization parameter μ=0.99, t_{c}=10 s, and an 800 km total repeater length, we obtain a secret key rate of 4.85 Hz, beating both the unencoded repeater that provides 1.25 Hz and ideal twin-field quantum key distribution with 0.71 Hz at GHz clock rates.http://doi.org/10.1103/PhysRevResearch.7.013117 |
| spellingShingle | Alena Romanova Peter van Loock Memory-corrected quantum repeaters with adaptive syndrome identification Physical Review Research |
| title | Memory-corrected quantum repeaters with adaptive syndrome identification |
| title_full | Memory-corrected quantum repeaters with adaptive syndrome identification |
| title_fullStr | Memory-corrected quantum repeaters with adaptive syndrome identification |
| title_full_unstemmed | Memory-corrected quantum repeaters with adaptive syndrome identification |
| title_short | Memory-corrected quantum repeaters with adaptive syndrome identification |
| title_sort | memory corrected quantum repeaters with adaptive syndrome identification |
| url | http://doi.org/10.1103/PhysRevResearch.7.013117 |
| work_keys_str_mv | AT alenaromanova memorycorrectedquantumrepeaterswithadaptivesyndromeidentification AT petervanloock memorycorrectedquantumrepeaterswithadaptivesyndromeidentification |